Alexandria, VA, United States
Alexandria, VA, United States

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Hegeler F.,Commonwealth Technology Inc. | McGeoch M.W.,PLEX LLC | Sethian J.D.,U.S. Navy | Sanders H.D.,Applied Pulsed Power Inc. | And 2 more authors.
IEEE Transactions on Dielectrics and Electrical Insulation | Year: 2011

A unique all solid-state pulsed power system has been tested at the Naval Research Laboratory that produced 200 kV, 4.5 kA, and 300 ns pulses, continuously for more than 11,500,000 shots into a resistive load at a repetition rate of 10 pps. The Marx has an efficiency of 80% based on calorimetric measurements. This pulser is used to evaluate components and advance solid state designs for a next generation solid-state pulsed power system to drive an electron beam pumped KrF laser system for inertial fusion energy. The solid state pulser, designed and constructed by PLEX LLC, consists of a 12 stage Marx, coupled with a 3rd harmonic stage to sharpen the Marx output waveforms, a main magnetic switch, a compact pulse forming line used as a transit time isolator, and a resistive load. Each Marx stage uses an APP Model S33A compact high voltage switch that consists of 12 series connected thyristors. A life test on individual thyristors showed operation of > 300 M shots at 20 Hz without failure. © 2011 IEEE.


Hegeler F.,Code | Hegeler F.,Commonwealth Technology Inc. | Friedman M.,Code | Myers M.C.,Code | And 2 more authors.
PPPS 2001 - Pulsed Power Plasma Science 2001 | Year: 2015

Electra is a repetitively pulsed, electron beam pumped krypton fluoride (KrF) laser that will be used to develop the technology required for inertial fusion energy (IFE). A full scale fusion KrF laser will be pumped with electron beams with cross-sections of 2,500 to 10,000 cm2. Understanding the mechanisms that govern uniform electron beam emission over such large areas is important for the overall system efficiency and durability. This paper presents measurements of the current density along the edge of a large area electron beam. The spatial and temporal current density data is obtained with a Faraday cup array at the anode, and the spatial time-integrated current density is obtained with radiachromic film. MAGIC particle-in-cell (PIC) simulations support the experimental results. Experiments and simulations showed that recessing the cathode minimizes the electric field at the edge and eliminates the edge effect. © 2002 IEEE.


Wolford M.F.,U.S. Navy | Sethian J.D.,U.S. Navy | Myers M.C.,U.S. Navy | Hegeler F.,Commonwealth Technology Inc. | And 2 more authors.
Plasma and Fusion Research | Year: 2013

The United States Naval Research Laboratory is developing an electron beam pumped krypton fluoride laser technology for a direct drive inertial fusion energy power plant. The repetitively pulsed krypton fluoride laser technology being developed meets the fusion energy requirements for laser beam quality, wavelength, and repetition rate. The krypton fluoride laser technology is projected, based on experiments, to meet the requirements for wall plug efficiency and durability. The projected wall plug efficiency based on experiments is greater than 7 percent. The Electra laser using laser triggered gas switches has conducted continuous operation for 90,000 shots at 2.5 Hertz operation (ten hours). The Electra laser has achieved greater than 700 Joules per pulse at 1 and 2.5 Hertz repetition rate. The comparison of krypton fluoride laser performance with krypton fluoride kinetics code shows good agreement for pulse shape and laser yield. Development and operation of a durable pulse power system with solid state switches has achieved a continuous run of 11 million pulses into a resistive load at 10 Hz. © 2013 The Japan Society of Plasma Science and Nuclear Fusion Research.


Wolford M.F.,U.S. Navy | Sethian J.D.,U.S. Navy | Myers M.C.,U.S. Navy | Hegeler F.,Commonwealth Technology Inc. | And 2 more authors.
Fusion Science and Technology | Year: 2013

The United States Naval Research Laboratory (NRL) is developing the krypton fluoride (KrF) laser technology for a direct drive laser inertial fusion energy (JFE) power plant. The overall projected wall plug efficiency for KrF laser system is ∼7%, including thermal management and optical losses. There are two KrF lasers at NRL. The first, Nike, provides up to 3 kJ of laser light per shot for experimental research in KrF laser-target interactions. The Electra Laser at NRL is a repetitively pulsed electron beam pumped 700 Joule KrF laser facility. The objective with Electra is to develop technologies to meet the IFE requirements for repetition rate, efficiency, and durability. Electra produces over 750 Joules in oscillator mode. Based on experiments, there is expected to be virtually no degradation in the laser focal profile, even at 5 Hz, high efficiency operation. Progress in durability has lead to achievement of KrF laser runs for 10 continuous hours at 2.5 Hz (90,000 shots) and 100 minutes at 5 Hz (over 30,000 shots). The main impediment to achieving long duration runs is the present pulsed power system that is based on spark gap switches. NRL has developed a new all solid state system that has operated for 11 million pulses continuously at 10 Hz and is based on components attaining 300 million pulses. These studies show an electron beam pumped KrF laser should be a viable approach for a laser fusion energy driver.


Myers M.C.,U.S. Navy | Hegeler F.,U.S. Navy | Hegeler F.,Commonwealth Technology Inc. | Friedman M.,U.S. Navy | Sethian J.D.,U.S. Navy
PPPS 2001 - Pulsed Power Plasma Science 2001 | Year: 2015

Electra [1] is a large aperture krypton-fluoride laser under development for inertial fusion energy research. The laser will require dual 500 kV, 36 A/cm2, uniform electron beams operating at 5 Hz. Experimental studies have been performed to develop a ∼3000 cm2, cathode capable of generating a 110 kA, 100 ns flat top beam pulse with minimal current density variation (< 10%), fast rise "time (<40 ns), negligible gap closure (<1 cm/μs), and long lifetime (ultimately 108 shots). Time resolved electrical and optical data from the study of various dielectric fiber, carbon, and metal/dielectric cathodes will be discussed. © 2002 IEEE.


Hegeler F.,U.S. Navy | Myers M.,Commonwealth Technology Inc. | Wolford M.F.,Commonwealth Technology Inc. | Sethian J.D.,Commonwealth Technology Inc. | Fielding A.M.,U.S. Navy
IEEE Transactions on Dielectrics and Electrical Insulation | Year: 2013

The Electra pulsed power system at the Naval Research Laboratory is capable of supplying 16 kJ to a low impedance load within 140 ns, and it allows continuous operation of up to 5 pulses per second for several hours. Four laser triggered SF6 gas switches transfer the stored pulse forming line energy to the load. Each switch has a hold-off voltage of more than 1 MV and transfers a charge of 10 mC per shot. This paper describes the redesign of the gas switch with hemispherical electrodes to a flat electrode configuration, which led to an improvement in switch reliability. A one sigma switch jitter of ±1.2 ns has been achieved for tens of thousands of continuous shots, with an electrode erosion rate as low as 1 mg/C. Detailed statistical analyses are provided when the switches are operated at a SF6 pressure of 0.36-0.69 MPa, with a laser trigger energy of 1-18 mJ at 266 nm, and a switch hold-off voltage ranging from 0.7-1.2 MV. © 1994-2012 IEEE.


Hegeler F.,Commonwealth Technology Inc. | Myers M.C.,U.S. Navy | Wolford M.F.,U.S. Navy | Sethian J.D.,U.S. Navy | Fielding A.M.,Commonwealth Technology Inc.
Proceedings of the 2012 IEEE International Power Modulator and High Voltage Conference, IPMHVC 2012 | Year: 2012

The Electra pulsed power system at the Naval Research Laboratory uses four laser triggered SF6 gas switches to transfer the stored pulse forming line energy to the load. Each switch has a hold-off voltage of more than 1 MV and transfers a charge of up to 10.5 mC per shot, with a switch current peak amplitude of 60 kA. The gas switches were originally constructed with hemispherical shaped electrodes. Continuous operations at repetition rates of up to 5 pulses per second showed increases in the switch jitter and switch misfire rates. A redesign with flat electrodes, which provide a more uniform electric field in the switch gap, showed a decrease in switch jitter. © 2012 IEEE.


Wolford M.F.,U.S. Navy | Myers M.C.,U.S. Navy | Hegeler F.,Commonwealth Technology Inc. | Sethian J.D.,U.S. Navy
Physical Chemistry Chemical Physics | Year: 2013

A catalyst free approach for nitrogen oxides (NOx) removal has been developed at the United States Naval Research Laboratory. Our goals were to assess the ability of pulsed electron beam to enhance NOx removal at potential lower capital cost with greater efficiency than other large scale NOx removal methods. Removal efficiency over 95% has been attained for NOx concentrations of 1000 parts per million (ppm), 500 ppm and 200 ppm in nitrogen atmosphere. The NOx concentration dropped from 204 ppm to below 4.8 ppm after 10 shots supplying a total dose of 65 kGy. The resultant chemicals after catalyst free pulsed electron beam processing of NOx are nitrogen and oxygen, same as components of air. Pulsed electron beams in a catalyst free approach remove a larger percentage of NO x than continuous wave electron beam with a catalyst. Catalyst free approach removes issues of handling, collecting, transporting and efficiently distributing chemical byproducts. Pulsed electron beams are as efficient as continuous wave electron beams for small removal percentages and have a significant advantage at higher fractional removal percentages of NO x. Preferential destruction of NO species relative to the removal of NO2 species is observed in the pulsed electron beam reaction chamber. The energy required to remove a kilogram of NOx is nearly the same at pressures of 1.16 atmospheres and 1.02 atmospheres. © 2013 the Owner Societies.


Myers M.C.,U.S. Navy | Rose D.V.,Voss Scientific, LLC | Hegeler F.,Commonwealth Technology Inc. | Wolford M.F.,U.S. Navy | Sethian J.D.,U.S. Navy
Physics of Plasmas | Year: 2013

The self-pinched transport of a 0.5 MeV, 18 kA cylindrical electron beam has been studied experimentally and computationally. The relatively low voltage and high current required for materials surface modification applications leads to complicated beam dynamics as the Alfven limit is approached. Transport and focusing of the high ν/γ beam was done in a sub-Torr, neutral gas-filled, conducting tube in the ion-focused regime. In this regime, beam space charge forces are progressively neutralized to allow focusing of the beam by its self-magnetic field. The beam exhibits stable envelope oscillations as it is efficiently and reproducibly propagated for distances greater than a betatron wavelength. Experimental results follow the trends seen in 2-D particle-in-cell simulations. Results show that the input electron beam can be periodically focused to a peaked profile with the beam half-current radius decreased by a factor of 2.84. This results in an increase of a factor of 8 in beam current density. This focusing is sufficient to produce desired effects in the surface layers of metallic materials. © 2013 AIP Publishing LLC.


Various embodiments of a rotationally molded product and related apparatuses and methods are disclosed. For example, a method of encapsulating a foreign object in a rotationally molded product may include forming a pre-layer on a surface of a mold of a rotational molding machine, placing a foreign object on the pre-layer, loading a first charge of powder material in the mold, and rotating the mold while applying heat to the mold to form a first layer on the foreign object. The foreign object may be fully encapsulated between the pre-layer and the first layer.

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